Association Between Changes in Hemoglobin Concentration and Cardiovascular Risks and All-Cause Mortality Among Young Women

Investigation on the relationship between hemoglobin concentration and stroke risk: a bidirectional Mendelian randomization study

Background

The relationship between hemoglobin concentration and stroke has garnered significant interest in the research community. However, findings from published observational epidemiological studies on this relationship have been inconclusive. By using publicly available genome-wide association study (GWAS) aggregated statistics, a two-sample Mendelian randomization analysis is conducted to explore the causal relationship between hemoglobin concentration and stroke.

Methods

Summary statistics data from UK Biobank for hemoglobin concentration and from the FinnGen R9 and MEGASTROKE consortium for stroke are used. A series of quality control steps are taken to select eligible instrumental SNPs closely related to exposure. In order to make the conclusion more robust and reliable, several robust analysis methods are employed including inverse variance weighted, weighted median, MR-Egger regression, which are based on different assumptions of two-sample MR Analysis. Meanwhile, sensitivity analyses such as pleiotropy test and MR-Egg regression, are performed to mitigate horizontal pleiotropy and heterogeneity.

Results

The two-sample Mendelian randomized study indicates a negative association between hemoglobin concentration and stroke, suggesting that hemoglobin concentration acts as a protective factor against stroke. From the FinnGen database, there is a negative association between hemoglobin concentration and stroke, with an odds ratio (OR) of 0.82 and a 95% confidence interval (CI) of 0.73-0.92, p = 0.0006. Similarly, the MEGASTROKE database findings reinforce this observation. The negative association between hemoglobin concentration and stroke (OR: 0.91, 95%CI: 0.83-1.00, p = 0.040), ischemic stroke (OR: 0.87, 95%CI: 0.79-0.96, p = 0.004), and cardiogenic stroke (OR: 0.82, 95% CI: 0.69-0.99, p = 0.039) further suggests that higher hemoglobin levels might confer a protective effect against these conditions.

Conclusion

Hemoglobin concentration serves as a protective factor against stroke, and managing abnormal hemoglobin levels can effectively reduce the incidence of stroke.

Relationship Between Hemoglobin Concentration and Cardiovascular Disease Mortality in a 25-Year Follow-up Study of a Japanese General Population - NIPPON DATA90

BACKGROUND

Deviations of hemoglobin from normal levels may be a factor in cardiovascular disease (CVD) risk; however, conclusive evidence is lacking. In addition, preclinical conditions may influence hemoglobin concentrations, but studies focusing on reverse causation are limited. Thus, we examined the relationship between hemoglobin concentrations and CVD mortality risk, considering reverse causation.Methods and Results: In a prospective cohort representative of the general Japanese population (1990-2015), we studied 7,217 individuals (mean age 52.3 years; 4,219 women) without clinical CVD at baseline. Participants were categorized into sex-specific hemoglobin quintiles (Q1-Q5) and data were analyzed using the Cox proportional hazards model adjusted for possible confounders. During a 25-year follow-up, 272 men and 334 women died from CVD. Adjusted hazard ratios for CVD mortality across sex-specific quintiles, using Q3 as the reference, were significantly higher for Q1 (1.40; 95% confidence interval [CI] 1.08-1.82) and Q5 (1.49; 95% CI 1.14-1.96), and remained significant after excluding deaths within the first 5 years of follow-up to consider reverse causation (1.35 [95% CI 1.02-1.79] and 1.45 [95% CI 1.09-1.94], respectively). A similar U-shaped association was seen between transferrin saturation levels and CVD mortality, but after excluding deaths within the first 5 years the association was significant only for Q1.

CONCLUSIONS

Low and high hemoglobin concentrations were associated with an increased risk of CVD mortality.

Association between short-term air pollution exposure and perturbation in thyrotropin levels in 1.38 million Chinese women: A national longitudinal analysis, 2014-2019

Prevalence of subclinical hypothyroidism substantially increased during the last decade in China, which has been commonly/clinically diagnosed as elevation in thyrotropin (thyroid-stimulating hormone [TSH]). Tobacco smoke containing toxic substances has been linked to thyroid dysfunction; however, data on perturbation of TSH following air pollution exposure in human has not been assessed at nationwide population level. We investigated the longitudinal impact of daily ambient air pollution estimated at residential level on serum TSH in 1.38 million women from China's 29 mainland provinces between 2014 and 2019. We observed that particulate matter with aerodynamic diameter ≤ 10 and ≤ 2.5 µm (PM10, PM2.5) and nitrogen dioxide (NO2) at cumulative lag 0-7 days of exposure were associated with percent elevations in TSH (0.88% [95% CI: 0.71, 1.05] per [interquartile range, IQR: 54.8 μg/m3] of PM10; 0.89% [95% CI, 0.71, 1.07] per IQR [40.3 μg/m3] of PM2.5; 2.01% [95% CI: 1.81, 2.22] per IQR [27.4 μg/m3] of NO2). Greater associations were observed in participants living in areas with ≥adequate iodine intake and those with low BMI levels and high inflammation status. Our results suggest that increased concentrations of recent ambient air pollutants at exposure ranges commonly encountered in Asia were associated with increases in TSH, supporting disturbing role of short-term air pollution exposure on the regulation of thyroid hormone homeostasis.

Trends in haemoglobin levels from 1968 to 2017 and association with hormonal contraceptives: observations from the population study of women in Gothenburg, Sweden

AIM

To investigate trends in the haemoglobin (Hb) level in middle-aged Swedish women from 1968 to 2017 and to examine the potential association between Hb and the use of hormonal contraceptives (HCs).

DESIGN

A prospective observational population study of representative 38- and 50-year-old women of Gothenburg, Sweden.

SETTING

The population study of women in Gothenburg started in 1968-1969 and has continued since then with new examinations every 12 years, including both follow-ups and new recruited cohorts. The study consists of both physical examinations and questionnaires.

SUBJECTS

Two thousand four hundred eighty-eight women aged 38 and 50 participated in the study from 1968 to 2017.

STATISTICAL METHODS

Linear regression model analyses were used to analyse linear and non-linear trends in the level of Hb. Linear and logistic regression models were used to analyse possible associations between HC and Hb and possible associations between the use of HC and anaemia, respectively.

MAIN OUTCOME MEASURES AND COVARIATES

Hb was measured in g/L. HC included any ongoing use of HC therapy. Covariates were smoking, body mass index (BMI), alcohol consumption and education.

RESULTS

A non-linear U-shaped trend in mean Hb was seen in the two age groups, 38- and 50-years old. After adjusting for covariates, a significantly higher mean Hb was seen in the 2016-2017 examination compared to 1980-1981, 1992-1993 and 2004-2005. In 38-year-olds, using HC was associated with a reduced risk of anaemia (OR 0.35, 95% CI 0.13-0.75). In both age groups, the use of HC was significantly associated with having a higher Hb.

CONCLUSIONS

Mean levels of Hb in middle-aged women of the general population seem to be increasing again after lower levels in the 1980s and 1990s. The use of HC was associated with having a higher Hb and a lower risk of anaemia in 38-year-old women.

Association of hemoglobin variability with the risk of cardiovascular disease: a nationally representative retrospective cohort study from South Korea

Hemoglobin variability is known to increase cardiovascular mortality in chronic kidney disease, but the association of hemoglobin variability with the risk of cardiovascular disease (CVD) in the general population is yet unclear. This retrospective cohort study based on 'the South Korean National Health Insurance Service database' consisted of 198,347 adults who went through all three health examinations. Hemoglobin variability is defined as the average successive variability of three separate hemoglobin values from each health screening period. Participants were followed up for 6 years to determine the risk of coronary heart disease and stroke. We used multivariate Cox proportional hazards regression to examine the adjusted hazard ratios for CVD according to hemoglobin variability. Per 1 unit increase of hemoglobin variability, the risk for CVD (aHR 1.06, 95% CI 1.02-1.09) and stroke (aHR 1.08, 95% CI 1.03-1.13) increased significantly. The risk-increasing trend was preserved in the low-to-moderate risk group of CVDs (aHR 1.07, 95% CI 1.02-1.11). This result suggests that subjects with high hemoglobin variability who would otherwise be categorized as having low-to-moderate CVD risk may have higher risk of CVD than those with low hemoglobin variability.

Is Hemoglobin Concentration a Linear Predictor of Mortality in Older Adults From Chinese Longevity Regions?

Introduction: The association patterns of hemoglobin (HB) concentrations with mortality among the longevity older adults are unclear. We aimed to evaluate the relationship among older adults form Chinese longevity regions. Methods: We included 1,785 older adults aged ≥65 years (mean age, 86.7 years; 1,002 women, 783 men) from the community-based Chinese Longitudinal Healthy Longevity Survey. We estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality using multivariable Cox proportional hazards models and Cox models with restricted cubic spline. Results: In total, 999 deaths occurred during a median follow-up of 5.4 years from 2011 to 2017. Restricted cubic spline analysis found no non-linear association between HB concentrations and all-cause mortality after a full adjustment for covariates among the older adults form longevity regions (p > 0.05 for non-linearity). The risk for all-cause mortality was significantly higher in the groups with HB concentration of <11.0 g/dL (HR: 1.37, 95% CI: 1.10-1.70) and 11.0-12.0 g/dL (HR: 1.25, 95% CI: 1.01-1.54); the risk of all-cause mortality was significantly lower in the groups with HB concentration ≥14.0 g/dL (HR: 0.76, 95% CI: 0.60-0.97) compared with the reference group (13.0-13.9 g/dL). Conclusions: Among older adults form Chinese longevity regions, HB concentrations were found to be inversely and linearly associated with all-cause mortality. Further prospective intervention trials are needed to confirm whether higher HB concentrations had a lower risk of mortality in these older adults.

Prediction of Mortality Associated with Cardiac and Radiological Findings in Patients with Pulmonary Embolism

Background: In this study, we aimed to compare echocardiography, electrocardiography (ECG) abnormalities, Doppler ultrasonography (USG), and computed tomography pulmonary angiography (CTPA) results in predicting 3-month mortality in patients with acute pulmonary embolism (PE).

Methods: This retrospective cohort study included 124 patients (72 females, 52 males) with acute PE. Demographics, symptoms, clinical signs, comorbidities, history of surgery, arterial blood gas, liver-renal functions, complete blood count, echocardiography, ECG, Doppler USG, and CTPA results, as well as 3-month mortality were recorded.

Results: pH (z = –2.623; p <0.01), hemoglobin (z = –3.112; p <0.01), and oxygen saturation (z = –2.165; p <0. 01) were significantly higher in survivors. White blood cell (z = –2.703; p <0.01), blood urea nitrogen (z = –3.840; p <0.01), creatinine (z = –3.200; p <0.01), respiratory rate (z = –2.759; p <0.01), and heart rate (z = –2.313; p <0.01) were significantly higher in non-survivors. Nonspecific ST changes (AUC 0.52, 95% CI 0.43–0.61), p pulmonale (AUC 0.52, 95% CI 0.43–0.61), normal axis (AUC 0.61), right axis deviation (AUC 0.56), right ventricle strain pattern (AUC 0.59), and right pulmonary artery embolism (AUC 0.54) on CTPA showed the highest mortality prediction.

Conclusions: Nonspecific ST changes, p pulmonale, normal axis and right axis deviation in ECG, RV strain in echocardiography, and right pulmonary artery embolism on CTPA are associated with a higher mortality in patients with PE.

Anemia is associated with the risk of Crohn's disease, not ulcerative colitis: A nationwide population-based cohort study

Anemia is a common manifestation of inflammatory bowel disease (IBD), but it remains unclear whether anemia is associated with the development of IBD. We assessed the risk of developing IBD in anemic patients, and stratified the results with respect to their hemoglobin concentrations. A population-based study was conducted using the National Healthcare Insurance Service database in South Korea. We included individuals over 20 years’ old who participated in the national health screening program in 2009 (n = 9,962,064). Anemia was defined as a hemoglobin level less than 13 g/dL in men and less than 12 g/dL in women. We compared the rate of newly diagnosed IBD in anemic patients and non-anemic individuals. Newly diagnosed IBD was identified using both the ICD-10 medical code and specialized V codes for rare intractable diseases in South Korea. During the mean follow-up period of 7.3 years, the incidences of CD and UC in anemic patients were 2.89 and 6.88 per 100,000 person-years, respectively. The risk of CD was significantly higher in anemic patients than in non-anemic individuals [adjusted hazard ratio (aHR), 2.084; 95% confidence interval (CI), 1.769–2.455]. The risk of CD development was inversely proportional to the hemoglobin concentration. A J-curve relationship was observed between age and the risk of CD in anemic patients. The risk of CD in male anemic patients was significantly higher than that in female anemic patients (aHR, 1.432 vs. 1.240, respectively). By contrast, there was no statistically significant difference in the risk of developing UC in anemic and non-anemic individuals (aHR, 0.972; 95% CI, 0.880–1.073). This work indicates that anemia is related to the development of CD, and this risk was inversely proportional to the hemoglobin concentration.

Impact of Genetically Predicted Red Blood Cell Traits on Venous Thromboembolism: Multivariable Mendelian Randomization Study Using UK Biobank

Background

Red blood cell (RBC) transfusion and erythropoiesis‐stimulating agent administration are cornerstones of clinical practice, yet concerns exist as to potential increased risk of thrombotic events. This study aims to identify RBC traits most relevant to venous thromboembolism (VTE) and assess their genetically predicted effects on VTE in the general population.

Methods and Results

We used multivariable mendelian randomization with bayesian model averaging for exposure selection. We obtained genetic variants predicting any of 12 RBC traits from the largest genome‐wide association study of hematological traits (173 480 participants of European ancestry) and applied them to the UK Biobank (265 424 white British participants). We used univariable mendelian randomization methods as sensitivity analyses for validation. Among 265 424 unrelated participants in the UK Biobank, there were 9752 cases of VTE (4490 men and 5262 women). Hemoglobin was selected as the plausible important RBC trait for VTE (marginal inclusion probability=0.91). The best‐fitting model across all RBC traits contained hemoglobin only (posterior probability=0.46). Using the inverse variance–weighted method, genetically predicted hemoglobin was positively associated (odds ratio, 1.21 per g/dL unit of hemoglobin; 95% CI, 1.05–1.41) with VTE. Sensitivity analyses (mendelian randomization–Egger, weighted median, and mendelian randomization pleiotropy residual sum and outlier test) gave consistent estimates.

Conclusions

Endogenous hemoglobin is the key RBC trait causing VTE, with a detrimental effect in the general population on VTE. Given men have higher hemoglobin than women, this finding may help explain the sexual disparity in VTE rates. The benefits of therapies and other factors that raise hemoglobin need to be weighed against their risks.

A Portable Smartphone-linked Device for Direct, Rapid and Chemical-Free Hemoglobin Assay

We describe the development and clinical evaluation of an automated smartphone-linked sensor capable of chemical-free, quantitative measurement of hemoglobin concentration ([Hb]) in whole blood samples. We have demonstrated that our sensor could analyze an unprocessed blood specimen with a mean processing time of <8 s and provided the [Hb] results with ~99% accuracy against a reference hematology analyzer with coefficient of variation (CV) of 1.21% measured at [Hb] = 11.2 g/dL. Its diagnostic capability for anemia was evaluated by measuring [Hb] of 142 clinical blood specimens and comparing the results with those from an automated hematology analyzer (ADVIA 2120i, Siemens AG, Germany) and a portable hemoglobinomteter (Hb201+, Hemocue, Sweden). The sensor yielded comparable sensitivities and specificities of 87.50% and 100.00% for males, and 94.44% and 100.00% for females, respectively, for anemic detection. The results suggested that our optical sensor based on the intrinsic photothermal response of Hb molecules and advances in consumer electronics, particularly smartphone capabilities, enables a direct, chemical-free [Hb] assay accessible to people in both developed and developing countries.

Noninvasive indices for predicting nonalcoholic fatty liver disease in patients with chronic kidney disease

Background

Data on clinical characteristics of nonalcoholic fatty liver disease (NAFLD) in patients with chronic kidney disease (CKD) are scarce. We investigated the clinical features and risk factors of NAFLD using noninvasive serum markers in CKD patients and attempted the temporal validation of a predictive model for CKD based on NAFLD.

Methods

This retrospective cross-sectional study was conducted in a single tertiary center. We enrolled 819 CKD patients and evaluated the predictive performance of relevant clinical and laboratory markers for the presence of NAFLD in both derivation (data from 2011 to 2014, n = 567) and validation (data from 2015 to 2016, n = 252) groups.

Results

In the derivation group, NAFLD was observed in 89 patients (15.7%; mean body mass index (BMI), 24.6 kg/m²; median estimated glomerular filtration rate (eGFR), 28.0 ml/min). BMI, hemoglobin, serum alanine aminotransferase, eGFR, and triglyceride-glucose index were used to derive a prediction model for the presence of NAFLD. Using the cutoff value of 0.146, the area under the receiver operating characteristic curve (AUROC) for the prediction of NAFLD was 0.850. In the validation group, NAFLD was observed in 51 patients (20.2%; mean BMI, 25.4 kg/m²; median eGFR, 36.0 ml/min). Using the same prediction model and cutoff value, the AUROC was 0.842. NAFLD prevalence in CKD patients was comparable to that in the general population, increasing over time.

Conclusions

Our model using BMI, renal function, triglyceride-glucose index, serum alanine aminotransferase, and hemoglobin accurately predicted the presence of NAFLD in CKD patients.

Trajectories of Haemoglobin and incident stroke risk: a longitudinal cohort study

Background

Studies have demonstrated that high or low haemoglobin increases the risk of stroke. Previous studies, however, performed only a limited number of haemoglobin measurements, while there are dynamic haemoglobin changes over the course of a lifetime. This longitudinal cohort study aimed to classify the long-term trajectory of haemoglobin and examine its association with stroke incidence.

Methods

The cohort consisted of 11,431 participants (6549 men) aged 20 to 50 years whose haemoglobin was repeatedly measured 3–9 times during 2004–2015. A latent class growth mixture model (LCGMM) was used to classify the long-term trajectory of haemoglobin concentrations, and hazard ratios (HRs) and 95% confidence intervals (95% CI) according to the Cox proportional hazard model were used to investigate the association of haemoglobin trajectory types with the risk of stroke.

Results

Three distinct trajectory types, high-stable (n = 5395), normal-stable (n = 5310), and decreasing (n = 726), were identified, with stroke incidence rates of 2.7, 1.9 and 3.2 per 1000 person-years, respectively. Compared to the normal-stable group, after adjusting for the baseline covariates, the decreasing group had a 2.94-fold (95% CI 1.22 to 7.06) increased risk of developing stroke. Strong evidence was observed in men, with an HR (95% CI) of 4.12 (1.50, 11.28), but not in women (HR = 1.66, 95% CI 0.34, 8.19). Individuals in the high-stable group had increased values of baseline covariates, but the adjusted HR (95% CI), at 1.23 (0.77, 1.97), was not significant for the study cohort or for men and women separately.

Conclusions

This study revealed that a decreasing haemoglobin trajectory was associated with an increased risk of stroke in men. These findings suggest that long-term decreasing haemoglobin levels might increase the risk of stroke.